requirement vs must

requirement and must both are nouns.

Word	Noun	Adjective	Verb	Adverb
requirement	Yes	No	No	No
must	Yes	Yes	No	No

As nouns, must is a hyponym of requirement; that is, must is a word with a more specific, narrower meaning than requirement:

Other hyponyms of requirement include desideratum, need, want.

requirement (noun)	must (noun)
something that is required in advance	the quality of smelling or tasting old or stale or mouldy
required activity	grape juice before or during fermentation
anything indispensable	a necessary or essential thing

requirement (adjective)	must (adjective)
	highly recommended